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Virginia big-eared bat

The Virginia big-eared bat (Corynorhinus townsendii virginianus) had a population of about 3,500 bats when it was listed as an endangered species in 1979 [9]. It increased to about 10,000 during the 1980s [2], 15,000 during the 1990s [3, 4], and was estimated at 18,442 bats after the last count in 2000 [4].

VIRGINIA
Virginia has two important big-eared bat caves, both in Tazewell County [1]. Tazewell County #1 is a maternity cave accessed by 10' deep hole in the earth. The known population has increased from 100 in 1978 and 80 in 1985 to an average of about 400 between 1991 and 2002. It was not surveyed in 2003-2005. It is unclear whether the increase is due to better survey techniques or population growth.

Tazewell Count #2 is both a maternity and hibernacula cave. The maternity population grew from the 200s in 1991 and 1992 to an average of about 550 from 1993 to 1999. Equipment failure precluded a 2002 count, but the surveyors believed the population size to be similar to previous years. The hibernacula was estimated at 2,000 bats between 1985 and 1990 based on subjective reports by cavers. Systematic surveys began in 1993. Prior to construction of a protective gate, the population was 476 in 1993 and 525 in 1995. The post-gate population was 1,600 in 1996 and 1,160 in 1999, with the latter year considered low due to unusual warmth. Surveys were discontinued in 2001 due to safety concerns over the unstable 100+ foot drop entrance.

The overall Virginia trend suggests a increase in the observed maternity population to about 950 females in the 1990s, and an increase in the hibernacula population to about 1,600 observed bats. Based these observed numbers, the state population has been estimated at about 2,200 bats [2, 3, 4].

NORTH CAROLINA
The population grew from 160 bats in 1992 [3] to 260 in 2000 [4].

KENTUCKY
Kentucky supports one major hibernaculum (Stillhouse Cave) which is surveyed every odd year [8]. It remained stable with about 1,000 bats from 1964 to 1974, then increased steadily 6,335 in 2001, before declining to 4,370 in 2005. The statewide population increased from 3,850 in 1992 [3] to 5,105 in 2000 [4].

WEST VIRGINIA
West Virginia has ten occupied big-eared bat caves [6]. The eight cave systematically surveyed between 1983 and 2005 grew relatively steadily from 3,327 bats to 4,889. All ten caves were systematically surveyed from 1992 to 2005, growing from 5,699 bats to 6,238 in 2004 before declining to 5,990 in 2005.

- The Arbogast/Cave Hollow population increased from 650 bats (1983) to 1,137 (1988) after a year-round closure was instituted and fence erected [5]. Vandals broke into the cave and built a fire near the maternity roost site between June 1988 and June 1989, reducing the population to 286 bats in 1989. The entrance was subsequently gated and the population slowly but steadily climbed to 648 in 2005 [6].

- The Lambert Cave population declined between 1999 and 200 when the large tree next to its entrance died, allowing sunlight to increase herbaceous vegetation which blocked the entrance [7]. The West Virginia Department of Natural Resources has controlled the vegetation and planted a new tree at the site, causing the population to bounce back.

- The Cliff maternity site was discovered in 1992 and was the first or second largest through 2005 [6].